mm: memcontrol: drop @compound parameter from memcg charging API

The memcg charging API carries a boolean @compound parameter that tells
whether the page we're dealing with is a hugepage.
mem_cgroup_commit_charge() has another boolean @lrucare that indicates
whether the page needs LRU locking or not while charging.  The majority of
callsites know those parameters at compile time, which results in a lot of
naked "false, false" argument lists.  This makes for cryptic code and is a
breeding ground for subtle mistakes.

Thankfully, the huge page state can be inferred from the page itself and
doesn't need to be passed along.  This is safe because charging completes
before the page is published and somebody may split it.

Simplify the callsites by removing @compound, and let memcg infer the
state by using hpage_nr_pages() unconditionally.  That function does
PageTransHuge() to identify huge pages, which also helpfully asserts that
nobody passes in tail pages by accident.

The following patches will introduce a new charging API, best not to carry
over unnecessary weight.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-4-hannes@cmpxchg.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 17 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 21438278afca..6b8c5900e9a4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2676,7 +2676,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		}
 	}
 
-	if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg, false))
+	if (mem_cgroup_try_charge_delay(new_page, mm, GFP_KERNEL, &memcg))
 		goto oom_free_new;
 
 	__SetPageUptodate(new_page);
@@ -2711,7 +2711,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		 */
 		ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
 		page_add_new_anon_rmap(new_page, vma, vmf->address, false);
-		mem_cgroup_commit_charge(new_page, memcg, false, false);
+		mem_cgroup_commit_charge(new_page, memcg, false);
 		lru_cache_add_active_or_unevictable(new_page, vma);
 		/*
 		 * We call the notify macro here because, when using secondary
@@ -2750,7 +2750,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 		new_page = old_page;
 		page_copied = 1;
 	} else {
-		mem_cgroup_cancel_charge(new_page, memcg, false);
+		mem_cgroup_cancel_charge(new_page, memcg);
 	}
 
 	if (new_page)
@@ -3193,8 +3193,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		goto out_page;
 	}
 
-	if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL,
-					&memcg, false)) {
+	if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL, &memcg)) {
 		ret = VM_FAULT_OOM;
 		goto out_page;
 	}
@@ -3245,11 +3244,11 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 	/* ksm created a completely new copy */
 	if (unlikely(page != swapcache && swapcache)) {
 		page_add_new_anon_rmap(page, vma, vmf->address, false);
-		mem_cgroup_commit_charge(page, memcg, false, false);
+		mem_cgroup_commit_charge(page, memcg, false);
 		lru_cache_add_active_or_unevictable(page, vma);
 	} else {
 		do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
-		mem_cgroup_commit_charge(page, memcg, true, false);
+		mem_cgroup_commit_charge(page, memcg, true);
 		activate_page(page);
 	}
 
@@ -3285,7 +3284,7 @@ unlock:
 out:
 	return ret;
 out_nomap:
-	mem_cgroup_cancel_charge(page, memcg, false);
+	mem_cgroup_cancel_charge(page, memcg);
 	pte_unmap_unlock(vmf->pte, vmf->ptl);
 out_page:
 	unlock_page(page);
@@ -3359,8 +3358,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	if (!page)
 		goto oom;
 
-	if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL, &memcg,
-					false))
+	if (mem_cgroup_try_charge_delay(page, vma->vm_mm, GFP_KERNEL, &memcg))
 		goto oom_free_page;
 
 	/*
@@ -3386,14 +3384,14 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	/* Deliver the page fault to userland, check inside PT lock */
 	if (userfaultfd_missing(vma)) {
 		pte_unmap_unlock(vmf->pte, vmf->ptl);
-		mem_cgroup_cancel_charge(page, memcg, false);
+		mem_cgroup_cancel_charge(page, memcg);
 		put_page(page);
 		return handle_userfault(vmf, VM_UFFD_MISSING);
 	}
 
 	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
 	page_add_new_anon_rmap(page, vma, vmf->address, false);
-	mem_cgroup_commit_charge(page, memcg, false, false);
+	mem_cgroup_commit_charge(page, memcg, false);
 	lru_cache_add_active_or_unevictable(page, vma);
 setpte:
 	set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
@@ -3404,7 +3402,7 @@ unlock:
 	pte_unmap_unlock(vmf->pte, vmf->ptl);
 	return ret;
 release:
-	mem_cgroup_cancel_charge(page, memcg, false);
+	mem_cgroup_cancel_charge(page, memcg);
 	put_page(page);
 	goto unlock;
 oom_free_page:
@@ -3655,7 +3653,7 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
 	if (write && !(vma->vm_flags & VM_SHARED)) {
 		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
 		page_add_new_anon_rmap(page, vma, vmf->address, false);
-		mem_cgroup_commit_charge(page, memcg, false, false);
+		mem_cgroup_commit_charge(page, memcg, false);
 		lru_cache_add_active_or_unevictable(page, vma);
 	} else {
 		inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
@@ -3864,8 +3862,8 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf)
 	if (!vmf->cow_page)
 		return VM_FAULT_OOM;
 
-	if (mem_cgroup_try_charge_delay(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
-				&vmf->memcg, false)) {
+	if (mem_cgroup_try_charge_delay(vmf->cow_page, vma->vm_mm,
+					GFP_KERNEL, &vmf->memcg)) {
 		put_page(vmf->cow_page);
 		return VM_FAULT_OOM;
 	}
@@ -3886,7 +3884,7 @@ static vm_fault_t do_cow_fault(struct vm_fault *vmf)
 		goto uncharge_out;
 	return ret;
 uncharge_out:
-	mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
+	mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg);
 	put_page(vmf->cow_page);
 	return ret;
 }